The present invention relates to decoding auxiliary information that is steganographically embedded in content data, and more particularly concerns decoding such information from content data that has been corrupted in some manner.
Media content, such as imagery (including video) and audio, can be encoded to convey hidden information (steganographic encoding) for a variety of purposes, including communication of auxiliary information (e.g., copyright data), authentication, tamper detection, forensic tracking, etc.
The reading (decoding) of the hidden information from the media content is complicated if the content has been corrupted in some manner. One example of corruption is the lossy compression/decompression associated with JPEG processing of digital imagery. In some cases, the corruption introduces errors in the decoding. In other cases, the corruption prevents the hidden information from being decoded at all.
In accordance with a preferred embodiment of the invention, reliable decoding of steganographically encoded information is enhanced by processing the corrupted media content so as to counteract some of the corruption. In accordance with another embodiment, the reading proceeds from the corrupted media content, but the results are processed in accordance with the corruption to which the content has been subjected.
The foregoing and additional features and advantages of the invention will be more readily apparent from the following detailed description, particularly including the section entitled Special Considerations for Recognizing Embedded Codes on Signals Which Have Been Compressed and Decompressed, or Alternatively, for Recognizing Embedded Codes Within Any Signal Which Has Undergone Some Known Process Which Creates Non-Uniform Error Sources found on page 39 of the typed specification